PROJECT SUMMARY As the most common neonatal sensory disorder in the United States, infant hearing loss has an incidence of 1.7 per 1000 births. The consequences of delayed diagnosis and failure to obtain timely intervention include significant communication impairment and negative socioeconomic effects. The overall lifetime medical, educational, and occupational costs due to deafness is estimated to be over $2.1 billion. Early detection of hearing may prevent language development and learning disorders. National standards dictate that all infants should be screened by 1 month of age, diagnosed by 3 months of age, and initiate treatment by 6 months of age (1-3-6 rule) and no more than 10% of infants should be non-adherent to diagnosis within 3 months after birth. In 2015, 59.4% of U.S. infants failed to obtain a diagnosis within 3 months after abnormal screening. There is a need for the development and implementation of interventions that promote adherence to timely diagnosis and treatment standards. Early infant hearing detection and intervention (EHDI) programs are coordinated on a state level, and the diagnostic process is complex and difficult for parents to navigate. Families of children with hearing loss report that they lack confidence and support in obtaining care for their child. Patient navigator (PN) programs have improved adherence to recommended diagnostic testing in cancer care after the detection of a screening abnormality, resulting in substantial healthcare system cost savings. PNs are trained individuals who mitigate barriers to promote healthcare adherence by educating patients and improving self-efficacy. We have recently demonstrated the PN efficacy to decrease non-adherence with infant hearing diagnostic care; however, PN has yet to be tested in diverse communities or implemented into EHDI programs, and there is a gap in this field regarding effectiveness and implementation research on interventions to reduce non-adherence. The proposed research is a community-engaged, type 1 hybrid effectiveness- implementation trial of a PN intervention aimed at decreasing infant hearing diagnosis non-adherence after failed newborn hearing screening, delivered in state-funded EHDI clinics. Guided by our community advisory board and partners, we aim to 1) to test the effectiveness of PN to decrease non-adherence to receipt of infant hearing diagnosis within 3 months after birth using a stepped-wedge trial design, 2) investigate implementation outcomes and factors influencing implementation, and 3) determine the cost-effectiveness of PN from the perspective of third party payers. This study is significant because it aims to reduce non-adherence to timely infant diagnostic hearing testing to prevent life-long negative consequences. This research is innovative in testing an intervention not previously assessed in hearing healthcare within a state-funded EHDI program, and in integrating implementation research and cost-effectiveness methods with our effectiveness aim. Our results will impact the field by partnering with communities to inform the scale-up of this and other innovative patient supportive interventions to create efficient and effective EHDI programs and maximize public health impact.